Polycomb-group (PcG) proteins and associated histone modifications play pivotal roles in development, stem cell self-renewal and cancer.These proteins function in differ-ent transcriptional repressor complexes that epigenetically modify chromatin and participate in the establishment and maintenance of cell fates [1].Although many proteins have been reported to associate with PcG protein complexes for transcriptional repression, the recent discovery of a link between long intergenic non-coding RNAs (iincRNAs) and PcG proteins added another regulatory layer for the diverse functions of PcG proteins [2, 3].